A liquid crystal displays is a flat panel display device using liquid crystal to display images, and has advantages of thin, low drive power and low power consumption, and is widely used in display device industry. However, a liquid crystal display panel is not self-luminous and needs an independent backlight source. And, using light emitting diodes (LED) as a backlight source has advantages of energy saving, longer working life and smaller volume as comparing to cold cathode fluorescent lamps (CCFL). Hence using light emitting diodes to replace cold cathode fluorescent lamps as a backlight source has become the current development trend of liquid crystal displays.
Please refer to FIG. 1 which discloses a cross-sectional side view of a conventional backlight module applying LED. A backlight module 90 has a frame 91, a light guide plate 92, a plurality of optical films 93, housing 94 and two light bars 95. The frame 91 has perpendicular portions 911 formed on two side edges thereof. The light guide plate 92 is mounted on a center of the frame 91. The optical films 93 are mounted on a top of the light guide plate 92. The housing 94 covers an outer edge of the frame 91 and fixes the optical films 93 and the light guide plate 92 from top to bottom. The light bars 95 are mounted on inner sidewalls of the perpendicular portions 911, respectively, wherein each light bar 95 has several LED devices 951 having an emitting direction toward the light guide plate 92. The light bars 95 are usually fixed on the perpendicular portions 911 by fastening through screws or thermally conductive adhesive tapes.
However, when assembling the backlight module 90, screws or thermally conductive adhesive tapes need to be applied on the perpendicular portions 911, the use of screws or thermally conductive adhesive tapes will make the assembling work more complicated, and the light bars 95 might be damaged when screw fastening is too tight, or product consistency or other assembly problems might be affected due to position misalignment of the thermally conductive adhesive tapes. Meanwhile, carrying out the fastening or sticking work in limited space is difficult. Moreover, a problem also occurs that precise material preparation and management are difficult due to too many types of components. Besides, when the backlight module 90 is working, temperature around the light bars 95 rises obviously, and some LED devices 951 may be damaged due to overheating, and then changing the light bars 95 will be necessary. When changing the light bars 95, the light guide plate 92 and the optical films 93 generally need to be dismantled at first, wherein such process might pollute the light guide plate 92 and the optical films 93.
Hence, it is necessary to provide a backlight module and a light-bar fixing structure thereof to overcome the problems existing in the conventional technology.